Organosilicon compounds, production processes thereof, pressure-sensitive adhesive compositions containing the organosilicon compounds, self-adhesive polarizers and liquid crystal displays

ABSTRACT

Organosilicon compounds are represented by the following formula: 
                         
wherein R is a hydrolyzable group, R′ is an alkyl having 1 to 4 carbon atoms, A is an alkylene having 1 to 6 carbon atoms, X is O or S, Y is —NH— or S, L 1  and L 2  are C or N, Z and M are —NH—, O or S, R 1  to R 11  are H, alkyl having 1 to 6 carbon atoms, alkoxy or fluoroalkyl, or amino, m is 1 to 3, and n is 0 to 3. R 1  and R 2  or R 2  and R 3  may bonded together. R 5  and R 6  or R 9  and R 10  may directly bond together. R 4  and R 7  or R 8  and R 11  may form a ring skeleton. Their production processes, pressure-sensitive adhesive compositions, self-adhesive polarizers and LCDs are also disclosed.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional application of U.S. application Ser.No. 12/553,601, filed Sep. 3, 2009 now abandoned, in which thisnon-provisional application is based upon and claims priority under 35U.S.C. §119(a) on Japanese Patent Application No. 2008-227777, filedSep. 5, 2008, the entire contents of which are incorporated herein byreference.

TECHNICAL FIELD

This invention relates to organosilicon compounds, and more specificallyto organosilicon compounds capable of producing excellent bonding forcewith hydroxyl-containing matrix resins owing to the inclusion of two ormore functional groups having coordination property with active hydrogenatoms in hydroxyl groups or the like and hence, significantly improvingthe adhesion and rework capability between pressure-sensitive adhesivescontaining the matrix resins and base materials. The present inventionis also concerned with their production processes, pressure-sensitiveadhesive compositions containing the organosilicon compounds,self-adhesive polarizers having pressure-sensitive adhesive layersformed from the pressure-sensitive adhesive compositions, and liquidcrystal displays including the self-adhesive polarizers.

BACKGROUND ART

A silane coupling agent has two or more different functional groups inits molecule, and acts as a mediator for joining an organic material andan inorganic material together although such organic and inorganicmaterials can be hardly joined together in general. One of thefunctional groups is a hydrolyzable silyl group, and in the presence ofwater, forms a silanol group. As a result of a reaction with a hydroxylgroup on the surface of an inorganic material, the silanol group forms achemical bond with the surface of the inorganic material. The other oranother functional group is an organic reactive group such as a vinyl,epoxy, amino, (meth)acryl or mercapto group, which forms a chemical bondwith an organic material such as a synthetic resin. Making use of theseproperties, silane coupling agents are widely used as modifiers fororganic and inorganic resins, adhesion aids, various additives and thelike.

Among such applications of silane coupling agents, their application aspressure-sensitive adhesives is representative. For pressure-sensitiveadhesives to be used upon bonding liquid crystal cells and optical filmstogether, for example, there is an outstanding demand for still higheradhesion performance as a result of the move toward greater and widerliquid crystal displays (LCD).

In the case of LCDs, there is an ever-increasing move toward largerpanels, contrary to the early-stage expectation that a size increasebeyond 20 inches would be difficult. Major manufacturers have heretoforeconcentrated their efforts on the manufacture of small panels of 20inches and smaller. Responsive to such a trend in recent years, however,they are now actively introducing latest technologies to expand theirproduct range to larger sizes of 20 inches and greater.

As mentioned above, there is a trend toward larger glass panels for usein combination with various optical films upon manufacture of liquidcrystal display panels. If a defective product occurs at the time ofinitial bonding of an optical film to a liquid crystal cell, the opticalfilm may be removed from the liquid crystal cell, and then, the liquidcrystal cell may be washed to permit its reuse. If a conventionalpressure-sensitive adhesive having high adhesiveness is used, this highadhesiveness makes it difficult to remove the optical film upon itsseparation due to the high adhesiveness force and moreover, isaccompanied by a high potential risk of breaking the costly liquid cell.As a consequence, the use of such a conventional pressure-sensitiveadhesive leads to a significant increase in manufacturing cost.

Keeping in step with the move toward larger LCDs, attempts have,therefore, been continued to develop high-function pressure-sensitiveadhesives capable of satisfying various adhesion properties such asadhesiveness and rework capability. For example, Japanese Patent No.3022993 proposes an epoxysilane-containing, acrylic pressure-sensitiveadhesive composition for the purpose of providing a polarizer excellentin durability under an environment of high temperature and highhumidity.

Further, JP-A 8-104855 proposes a pressure-sensitive adhesivecomposition containing an acrylic polymer and a compound which has aβ-ketoester group and a hydrolyzable silyl group, not only to permitbonding a polarizer on the surface of a substrate with good adhesiveforce but also to permit removing the polarizer from the surface of thesubstrate as needed without giving damage to the substrate or allowingthe adhesive to remain.

It is described that owing to the inclusion of such a silane compound,the substrate and the polarizer can retain adequate adhesive force ofsuch a level as required in an actual use environment, the adhesiveforce does not become excessive by heating or the like, and thepolarizer can be readily removed without giving damage to the liquidcrystal device.

As performance required for a pressure-sensitive adhesive to support themove toward larger LCDs, it is necessary not only to produce low initialadhesive force upon bonding to glass and to assure excellent reworkcapability but also to develop high adhesive force under hightemperature and high humidity. Otherwise, there is a potential problemthat bubbling, separation and/or the like may take place to lower thedurability.

JP-A 8-199144 proposes a technology that incorporates a curing agent inan acrylic resin which is obtainable by polymerizing an acrylic monomerin the presence of a silane compound to provide a pressure-sensitiveadhesive composition that does not undergo much variations with time incohesive force and adhesive force even under high temperature and highhumidity and is also excellent in adhesive force for curved surfaces.

It is described that owing to the incorporation of the silane compound,the substrate and the polarizer can retain adequate adhesive force ofsuch a level as required in an actual use environment, the adhesiveforce does not become excessive by heating or the like, and thepolarizer can be readily removed without giving damage to the liquidcrystal device.

However, a pressure-sensitive adhesive composition is considered to bepreferred when it is high in adhesive force, free from bubbling orseparation and excellent in durability rather than when it does notundergo much variations with time in cohesive force and adhesive forceeven under high temperature and high humidity. In other words, it isconsidered necessary to show adequate initial adhesive force of such alevel as permitting removal of a polarizer in an initial stage after itsbonding to glass but, as time goes on, to be enhanced in adhesive forceand to retain stabilized adhesive force because it becomes no longernecessary to remove the polarizer.

As a pressure-sensitive adhesive low in initial adhesive force andexcellent in rework capability, and after bonding, enhanced in adhesiveforce under high temperature and high humidity and excellent indurability over long term, JP-T 2008-506028 proposes an acrylicself-sensitive adhesive composition containing a silane coupling agenthaving a urethane functional group and a pyridine functional group.

However, the silane coupling agent is obtained by reacting anisocyanatosilane and 2-pyridinol in the presence of a catalyst, and ahydroxyl group of 2-pyridinol non-selectively reacts to both theisocyanato group and hydrolyzable silyl group of the silane.Accordingly, the silane coupling agent does not have such a singlestructure as the disclosed silane, and is insufficient in theimprovements of various self-adhesion properties.

Under the foregoing circumstances, it has been desired to develop apressure-sensitive adhesive which has rework capability in an initialstage and retains high adhesiveness force under high temperature andhigh humidity.

CITATION LIST

-   Patent Document 1: Japanese Patent No. 3022993-   Patent Document 2: JP-A 8-104855-   Patent Document 3: JP-A 8-199144-   Patent Document 4: JP-T 2008-506028

SUMMARY OF THE INVENTION

It is therefore an object of the present invention to provide anorganosilicon compound capable of affording a pressure-sensitiveadhesive composition which can form a pressure-sensitive adhesive layerhaving low initial adhesiveness force and excellent rework capabilityupon bonding an optical film or the like on an adherend such as glassand exhibiting increased adhesive force with the adherend and excellentlong-term durability under conditions of high temperature or hightemperature and high humidity after the bonding; and a productionprocess of the organosilicon compound. Another object of the presentinvention is to provide a pressure-sensitive adhesive composition withsuch an organosilicon compound incorporated therein, a self-adhesivepolarizer having a pressure-sensitive adhesive layer formed from thepressure-sensitive adhesive composition and a liquid crystal displayhaving the self-adhesive polarizer.

To achieve the above-described objects, the present inventor hasenthusiastically conducted investigations. As a result, it has beenfound that a pressure-sensitive adhesive composition which satisfiesboth rework capability in an initial stage and high adhesiveness forceunder high temperature or high temperature and high humidity can beobtained by incorporating in an adhesive composition a silane couplingagent having two or more functional groups equipped with coordinationproperty with active hydrogen atoms in hydroxyl groups or the like andrepresented by one of the following formulas (1) to (3), leading to thecompletion of the present invention.

The present invention, therefore, provides the following organosiliconcompounds, production processes thereof, pressure-sensitive adhesivecomposition, self-adhesive polarizer, and liquid crystal display.

[1] An organosilicon compound represented by the following formula (1):

wherein R is a hydrolyzable group, R′ is an alkyl group having 1 to 4carbon atoms, A is a linear or branched alkylene group having 1 to 6carbon atoms, X is an oxygen atom or sulfur atom, Y is —NH— or a sulfuratom, L¹ and L² are each independently a carbon atom or nitrogen atom,R¹ to R³ are each independently a hydrogen atom, an alkyl, alkoxy orfluoroalkyl group having 1 to 6 carbon atoms, or an amino group, R¹ andR² or R² and R³ may bond together to form a ring skeleton with thecarbon atoms to which they are bonded and L², m is an integer of 1 to 3,and n is an integer of 0 to 3.[2] An organosilicon compound represented by the following formula (2):

wherein R is a hydrolyzable group, R′ is an alkyl group having 1 to 4carbon atoms, A is a linear or branched alkylene group having 1 to 6carbon atoms, X is an oxygen atom or sulfur atom, Z is —NH—, an oxygenatom or a sulfur atom, M is —NH—, an oxygen atom or a sulfur atom, R⁴ toR⁷ are each independently a hydrogen atom, an alkyl, alkoxy orfluoroalkyl group having 1 to 6 carbon atoms, or an amino group, R⁵ andR⁶ may directly bond together to form a double bond between the carbonatoms to which they are bonded, R⁴ and R⁷ may bond together to form analiphatic or aromatic ring skeleton together with the carbon atoms towhich they are bonded, m is an integer of 1 to 3, and n is an integer of0 to 3.[3] An organosilicon compound represented by the following formula (3):

wherein R is a hydrolyzable group, R′ is an alkyl group having 1 to 4carbon atoms, A is a linear or branched alkylene group having 1 to 6carbon atoms, X is an oxygen atom or sulfur atom, Z is —NH—, an oxygenatom or a sulfur atom, R⁸ to R¹¹ are each independently a hydrogen atom,an alkyl, alkoxy or fluoroalkyl group having 1 to 6 carbon atoms, or anamino group, R⁹ and R¹⁰ may directly bond together to form a double bondbetween the carbon atoms to which they are bonded, R⁸ and R¹¹ may bondtogether to form an aliphatic or aromatic ring skeleton together withthe carbon atoms to which they are bonded, m is an integer of 1 to 3,and n is an integer of 0 to 3.[4] A process for producing the organosilicon compound as describedabove [1], which includes reacting an iso(thio)cyanatosilane, which isrepresented by the following formula (4):

wherein R is a hydrolyzable group, R′ is an alkyl group having 1 to 4carbon atoms, A is a linear or branched alkylene group having 1 to 6carbon atoms, X is an oxygen atom or sulfur atom, and m is an integer of1 to 3, with a heterocyclic compound represented by the followingformula (5):

wherein Y is —NH— or a sulfur atom, L¹ and L² are each independently acarbon atom or nitrogen atom, R¹ to R³ are each independently a hydrogenatom, an alkyl, alkoxy or fluoroalkyl group having 1 to 6 carbon atoms,or an amino group, R¹ and R² or R² and R³ may bond together to form aring skeleton with the carbon atoms to which they are bonded and L², andn is an integer of 0 to 3.[5] A process for producing the organosilicon compound as describedabove [2], which includes reacting an iso(thio)cyanatosilane, which isrepresented by the following formula (4):

wherein R is a hydrolyzable group, R′ is an alkyl group having 1 to 4carbon atoms, A is a linear or branched alkylene group having 1 to 6carbon atoms, X is an oxygen atom or sulfur atom, and m is an integer of1 to 3, with a heterocyclic compound represented by the followingformula (6):

wherein Z is —NH—, an oxygen atom or a sulfur atom, M is —NH—, an oxygenatom or a sulfur atom, R⁴ to R⁷ are each independently a hydrogen atom,an alkyl, alkoxy or fluoroalkyl group having 1 to 6 carbon atoms, or anamino group, R⁵ and R⁶ may directly bond together to form a double bondbetween the carbon atoms to which they are bonded, R⁴ and R⁷ may bondtogether to form an aliphatic or aromatic ring skeleton together withthe carbon atoms to which they are bonded, and n is an integer of 0 to3.[6] A process for producing the organosilicon compound as describedabove [3], which includes reacting an iso(thio)cyanatosilane representedby the following formula (4):

wherein R is a hydrolyzable group, R′ is an alkyl group having 1 to 4carbon atoms, A is a linear or branched alkylene group having 1 to 6carbon atoms, X is an oxygen atom or sulfur atom, and m is an integer of1 to 3, with a heterocyclic compound represented by the followingformula (7):

wherein Z is —NH—, an oxygen atom or a sulfur atom, R⁸ to R¹¹ are eachindependently a hydrogen atom, an alkyl, alkoxy or fluoroalkyl grouphaving 1 to 6 carbon atoms, or an amino group, R⁹ and R¹⁰ may directlybond together to form a double bond between the carbon atoms to whichthey are bonded, R⁸ and R¹¹ may directly bond together to form analiphatic or aromatic ring skeleton together with the carbon atoms towhich they are bonded, and n is an integer of 0 to 3.[7] A pressure-sensitive adhesive composition including theorganosilicon compound as described any one of above [1] to [3].[8] The pressure-sensitive adhesive composition as described above [7],including:

(A) 100 parts by weight of a (meth)acrylic copolymer obtainable bycopolymerizing (a) 90 to 99.9 parts by weight of a (meth)acrylate estermonomer having an alkyl group having 1 to 12 carbon atoms and (b) 0.1 to10 parts by weight of at least one of a vinyl monomer and (meth)acrylicmonomer each of which contains a crosslinkable functional group,

(B) 0.01 to 10 parts by weight of a polyfunctional crosslinking agent,and

(C) 0.01 to 9 parts by weight of organosilicon compounds as describedany one of above [1] to [3].

[9] The pressure-sensitive adhesive composition as described above [8],wherein at least one of the vinyl monomer and (meth)acrylic monomer (b)is selected from a group consisting of 2-hydroxyethyl(meth)acrylate,3-hydroxypropyl(meth)acrylate, 4-hydroxybutyl(meth)acrylate, diethyleneglycol mono(meth)acrylate, dipropylene glycol mono(meth)acrylate,(meth)acryloxypropyltrimethoxysilane,(meth)acryloxypropyltriethoxysilane,(meth)acryloxypropylmethyldimethoxysilane,(meth)acryloxypropylmethyldiethoxysilane,(meth)acryloxymethyltrimethoxysilane,(meth)acryloxymethyltriethoxysilane,(meth)acryloxymethylmethyldimethoxysilane,(meth)acryloxymethylmethyldiethoxysilane, (meth)acrylic acid,(meth)acrylic acid dimmer, itaconic acid, maleic acid, and maleic acidanhydride.[10] The pressure-sensitive adhesive composition as described above [8]or [9], wherein the polyfunctional crosslinking agent (B) is at leastone crosslinking agent selected from a group consisting of isocyanatecompounds, epoxy compounds, aziridine compounds and metal chelatecompounds.[11] The pressure-sensitive adhesive composition as described above [7],which is cured into a product having a crosslink density of 5 to 95 wt%.[12] A self-adhesive polarizer including a polarizing film and apressure-sensitive adhesive layer formed from the pressure-sensitiveadhesive composition as described above [7] and applied on at least oneof opposite sides of the polarizing film.[13] The self-adhesive polarizer as described above [12], furtherincluding at least one layer selected from a group consisting of aprotective layer, a reflective layer, a retardation plate, an opticalview-angle compensation film, and a luminance enhancement film.[14] A liquid crystal display including a liquid crystal cell composedof a pair of glass substrates and a liquid crystal sealed between theglass substrates and the self-adhesive polarizer as described above [12]or [13] bonded on at least one of opposite sides of the liquid crystalcell.

ADVANTAGEOUS EFFECT OF THE INVENTION

Each organosilicon compound (silane coupling agent) according to thepresent invention has organic functional groups excellent incoordination property with active protons like hydrogen atoms inhydroxyl groups. A self-sensitive adhesive composition with theorganosilicon compound incorporated therein is excellent in reworkcapability in an initial stage because hydrogen bonds are formed betweenactive protons in chains on the side of a base polymer and thefunctional groups in the silane coupling agent. Moreover, the adhesiveforce increases with time under high temperature or high temperature andhigh humidity so that the self-sensitive adhesive composition isexcellent in long-term durability.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram showing a ¹H-NMR spectrum of the reaction product ofSynthesis Example 1;

FIG. 2 is a diagram showing a ¹³C-NMR spectrum of the reaction productof Synthesis Example 1;

FIG. 3 is a diagram showing a ²⁹Si-NMR spectrum of the reaction productof Synthesis Example 1;

FIG. 4 is a diagram showing an IR spectrum of the reaction product ofSynthesis Example 1; and

FIG. 5 is a diagram showing a GPC chart of the reaction product ofSynthesis Example 1.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

A description will hereinafter be made specifically about the presentinvention. It is to be noted that the term “silane coupling agent” asused herein is embraced in the term “organosilicon compound.”

Organosilicon Compounds (Silane Coupling Agents)

As a characteristic feature of each organosilicon compound (silanecoupling agent) according to the present invention, it is possible tomention that it has all of the following structures (i) to (iii):

-   (i) a heterocycle having at least one atom selected from nitrogen    atoms, oxygen atoms and sulfur atoms;-   (ii) a divalent organic group containing at least one bond selected    from (thio)urethane bond, (thio)urea bond, (thio)amide bond,    (thio)ester bond, amino bond, (thio)ether bond and sulfide bond; and-   (iii) a hydrolyzable silyl group.

The heterocycle of the structure (i), which has at least one of nitrogenatoms, oxygen atoms and sulfur atoms, can be an aliphatic ring oraromatic ring. Its specific structures include, but are not limited to,structures such as those to be described below.

wherein wavy lines indicate bonds.

In the present invention, no particular limitation is imposed on thehydrolyzable silyl group of the structure (iii) insofar as it is a silylgroup having at least one of a monovalent hydrolyzable atom bondeddirectly to a silicon atom (an atom capable of forming a silanol groupthrough a reaction with water) and a monovalent hydrolyzable groupbonded directly to a silicon atom (a group capable of forming a silanolgroup through a reaction with water). Such a hydrolyzable silyl groupundergoes hydrolysis to form a silanol group, and this silanol groupundergoes dehydration condensation with an inorganic material to form achemical bond of the formula: Si—O-M (M: inorganic material). Eachorganosilicon compound according to the present invention contains onlyone of such a hydrolyzable silyl group, and may contain two or more ofsuch hydrolyzable silyl groups. When two or more hydrolyzable silylgroups exist, they may be the same or different.

Examples of the hydrolyzable silyl group of the structure (iii) includechlorosilyl, bromosilyl, methoxysilyl, ethoxysilyl, propoxysilyl,butoxysilyl, and the like.

Preferred silane coupling agents according to the present inventioninclude those represented by the following formulas (1) to (3):

wherein R is a hydrolyzable group, R′ is an alkyl group having 1 to 4carbon atoms, A is a linear or branched alkylene group having 1 to 6carbon atoms, X is an oxygen atom or sulfur atom, Y is —NH— or a sulfuratom, L¹ and L² are each independently a carbon atom or nitrogen atom,R¹ to R³ are each independently a hydrogen atom, an alkyl, alkoxy orfluoroalkyl group having 1 to 6 carbon atoms, or an amino group, R¹ andR² or R² and R³ may bond together to form a ring skeleton with thecarbon atoms to which they are bonded and L², m is an integer of 1 to 3,and n is an integer of 0 to 3;

wherein R, R′, A, X, m and n are as defined above, Z is —NH—, an oxygenatom or a sulfur atom, M is —NH—, an oxygen atom or a sulfur atom, R⁴ toR⁷ are each independently a hydrogen atom, an alkyl, alkoxy orfluoroalkyl group having 1 to 6 carbon atoms, or an amino group, R⁵ andR⁶ may directly bond together to form a double bond between the carbonatoms to which they are bonded, and R⁴ and R⁷ may bond together to forman aliphatic or aromatic ring skeleton together with the carbon atoms towhich they are bonded; and

wherein R, R′, A, X, Z, m and n are as defined above, R⁸ to R¹¹ are eachindependently a hydrogen atom, an alkyl, alkoxy or fluoroalkyl grouphaving 1 to 6 carbon atoms, or an amino group, R⁹ and R¹⁰ may directlybond together to form a double bond between the carbon atoms to whichthey are bonded, and R⁸ and R¹¹ may directly bond together to form analiphatic or aromatic ring skeleton together with the carbon atoms towhich they are bonded.

In the above-described formulas, R can be a halogen atom such aschlorine or bromine, or an alkoxy group such as methoxy, ethoxy, propoxyor butoxy; and R′ can be an alkyl group such as methyl, ethyl or propyl.A can be, but is not limited to, a linear alkylene group such asmethylene, ethylene or propylene, or a branched alkylene group such asmethallyl, isopropylene or isobutylene. Further, R¹ to R³ can each be ahydrogen atom, an alkyl group such as methyl, ethyl or propyl, afluoroalkyl group formed by substituting some or all of the hydrogenatoms of such a group with a like number of fluorine atoms, an alkoxygroup such as methoxy, ethoxy or propoxy, or an amino group; or R¹ andR² or R² and R³ may bond together with the carbon atoms to which theyare bonded to form a ring such as cyclopentyl or cyclohexyl. R⁴ to R⁷can each be a hydrogen atom, an alkyl group such as methyl, ethyl orpropyl, a fluoroalkyl group formed by substituting some or all of thehydrogen atoms of such a group with a like number of fluorine atoms, analkoxy group such as methoxy, ethoxy or propoxy, or an amino group; orR⁵ and R⁶ may directly bond together to form a double bond between thecarbon atoms to which they are bonded, and/or R⁴ and R⁷ may bondtogether to form an aliphatic or aromatic ring skeleton together withthe carbon atoms to which they are bonded. R⁸ to R¹¹ can each be ahydrogen atom, an alkyl group such as methyl, ethyl or propyl, afluoroalkyl group formed by substituting some or all of the hydrogenatoms of such a group with a like number of fluorine atoms, an alkoxygroup such as methoxy, ethoxy or propoxy, or an amino group; or R⁹ andR¹⁰ may directly bond together to form a double bond between the carbonatoms to which they are bonded, and/or R⁸ and R¹¹ may bond together toform an aliphatic or aromatic ring skeleton such as cyclopentyl orcyclohexyl together with the carbon atoms to which they are bonded.

Specific examples of the silane coupling agents having coordinatefunction groups according to the present invention are represented bythe following structural formulas (8) to (15), in which Et represents anethyl group.

The above-described silane coupling agents can each form, with an activeproton such as the hydrogen atom in a hydroxyl group, a stablecoordinate bond such as that represented by the following formula (A):

wherein Q represents a nitrogen atom, sulfur atom, or oxygen atom.

The silane coupling agents according to the present invention can eachbe obtained by reacting an iso(thio)cyanatosilane coupling agent, whichis represented by the following formula (4):

wherein R is a hydrolyzable group, R′ is an alkyl group having 1 to 4carbon atoms, A is a linear or branched alkylene group having 1 to 6carbon atoms, X is an oxygen atom or sulfur atom, and m is an integer of1 to 3, with one of amine compound, mercapto compound and alcohol havingheterocyclic structures and represented by the below-described formulas(5) to (7).

The iso(thio)cyanatosilane can be commercially available. Specificexamples include, but are not limited to,isocyanatomethyltrimethoxysilane, isocyanatomethyltriethoxysilane,isocyanatoethyltrimethoxysilane, isocyanatoethyltriethoxysilane,isocyanatopropyltrimethoxysilane, isocyanatopropyltriethoxysilane,isothiocyanatopropytriethoxysilane, and the like.

The amine compound, mercapto compound and alcohol having theheterocyclic structures can be compounds represented by thebelow-described formulas (5) to (7).

wherein Y is —NH— or a sulfur atom, L¹ and L² are each independently acarbon atom or nitrogen atom, R¹ to R³ are each independently a hydrogenatom, an alkyl, alkoxy or fluoroalkyl group having 1 to 6 carbon atoms,or an amino group, R¹ and R² or R² and R³ may bond together to form aring skeleton with the carbon atoms to which they are bonded and L², andn is an integer of 0 to 3;

wherein Z is —NH—, an oxygen atom or a sulfur atom, M is —NH—, an oxygenatom or a sulfur atom, R⁴ to R⁷ are each independently a hydrogen atom,an alkyl, alkoxy or fluoroalkyl group having 1 to 6 carbon atoms, or anamino group, R⁵ and R⁶ may directly bond together to form a double bondbetween the carbon atoms to which they are bonded, R⁴ and R⁷ may bondtogether to form an aliphatic or aromatic ring skeleton together withthe carbon atoms to which they are bonded, and n is an integer of 0 to3; and

wherein Z is —NH—, an oxygen atom or a sulfur atom, R⁸ to R¹¹ are eachindependently a hydrogen atom, an alkyl, alkoxy or fluoroalkyl grouphaving 1 to 6 carbon atoms, or an amino group, R⁹ and R¹⁰ may directlybond together to form a double bond between the carbon atoms to whichthey are bonded, R⁸ and R¹¹ may bond together to form an aliphatic oraromatic ring skeleton together with the carbon atoms to which they arebonded, and n is an integer of 0 to 3.

In the above-described formulas, R¹ to R¹¹ can be similar to thosedescribed above. These compounds having the heterocyclic structures canbe those available on the market. Specific examples include, but are notlimited to, aminoimidazole, mercaptoimidazole, hydroxyimidazole,aminothiazole, mercaptothiazole, hydroxythiazole, aminothiazoline,mercaptothiazoline, hydroxythiazoline, aminopyridine, mercaptopyridine,hydroxypyridine, aminopyrimidine, mercaptopyrimidine, hydroxypyrimidine,aminotriazine, mercaptotriazine, hydroxytriazine, aminobenzothiazole,hydroxysuccinimide, hydroxyphthalimide, hydroxymethylphthalimide, andthe like.

Upon producing each silane coupling agent according to the presentinvention, no particular limitation is imposed on the mixing ratio ofthe amine compound, mercapto compound or alcohol having the heterocyclicstructure to the iso(thio)cyanatosilane. From the standpoints ofreactivity and productivity, however, it is preferred to react the aminecompound, mercapto compound or alcohol having the heterocyclic structurein a range of from 0.5 to 2 moles, especially from 0.8 to 1.2 moles permole of the iso(thio)cyanatosilane. If the mixing amount of the compoundhaving the heterocyclic structure is too little, theiso(thio)cyanatosilane may remain abundantly and may undergopolymerization to cause gelling. If too much, on the other hand, noeffects are given to various properties of the resulting silane couplingagent, but demerits may arise such that the resulting silane couplingagent would be provided with lowered purity and moreover, itsproductivity would be reduced.

Upon producing each silane coupling agent according to the presentinvention, an organic solvent may be used as needed. Describedspecifically, no particular limitation is imposed on the organicsolvent, insofar as it is reactive with neither the iso(thio)cyanatogroup and hydrolyzable silyl group in the reactantiso(thio)cyanatosilane coupling agent nor the amino group, mercapto orhydroxyl group in the reactant amine compound, mercapto compound oralcohol. More specific examples include, but are not limited to,aliphatic hydrocarbon solvents such as pentane, hexane and heptane;aromatic hydrocarbon solvents such as toluene and xylene; linear orcyclic ether solvents such as diethyl ether, cyclopentyl methyl ether,dioxane and tetrahydrofuran; ester solvents such as ethyl acetate andbutyl acetate; amide solvents such as formamide, dimethylformamide,pyrrolidone and N-methylpyrrolidone; ketone solvents such as acetone,methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone; and thelike.

Upon producing each silane coupling agent according to the presentinvention, a reaction catalyst may be used as needed. In general, use ofno catalyst in the reaction between an isocyanate compound and amercapto compound or alcohol may lead to low reaction velocity andinferior productivity. The reaction catalyst can be commerciallyavailable. Specifically, organotin compounds are preferred, withoctyltin compounds and organotin compounds having one or moresubstituent groups having at least 8 carbon atoms being more preferredin view of environmental load, although the reaction catalyst is notlimited to those exemplified above.

No particular limitation is imposed on the amount of the catalyst to beused. From the standpoints of reactivity and productivity, however, itis preferred to use the catalyst in a range of from 0.00001 to 0.1 partsby weight, notably from 0.0001 to 0.01 parts by weight per 1 part byweight of the silane compound. The use of the catalyst in an amount inthis range makes it easier to bring about sufficient reaction promotingeffect commensurate with the amount of the catalyst.

No particular limitation is imposed on the reaction temperature insofaras the iso(thio)cyanato group and the amino group, mercapto or hydroxylgroup can react with each other, although it may range preferably from 0to 200° C., notably from 10 to 150° C. The reaction time may rangepreferably from 10 minutes to 10 hours, notably from 30 minutes to 6hours. The atmosphere may preferably be the air atmosphere or an inertgas atmosphere such as nitrogen or argon.

As a result of the reaction between the iso(thio)cyanato group and theamino, mercapto or hydroxyl group, a (thio)urea bond or (thio)urethanebond having coordinate property is formed so that a silane couplingagent having coordinate functional groups is obtained.

Pressure-Sensitive Adhesive Composition

A description will next be made about the pressure-sensitive adhesivecomposition containing the above-described coordinate functional groups.

The pressure-sensitive adhesive composition according to the presentinvention may preferably include:

(A) 100 parts by weight of a (meth)acrylic copolymer obtainable bycopolymerizing (a) 90 to 99.9 parts by weight of a (meth)acrylate estermonomer with an alkyl group having 1 to 12 carbon atoms and (b) 0.1 to10 parts by weight of at least one of a vinyl monomer and (meth)acrylicmonomer each of which contains a crosslinkable functional group,(B) 0.01 to 10 parts by weight of a polyfunctional crosslinking agent,and(C) 0.01 to 9 parts by weight of an organosilicon compound representedby any one of the formulas (1) to (3).

The (meth)acrylate ester monomer with an alkyl group having 1 to 12carbon atoms (a) for use in the composition according to the presentinvention may be contained desirably in an amount of 90 to 99.9 parts byweight, notably in an amount of 91 to 99 parts by weight in 100 parts byweight of the monomers to be copolymerized. Its content lower than 90parts by weight may lead to a reduction in initial adhesive force, whileits content higher than 99.9 parts by weight may cause a problem indurability due to reduced cohesive force.

As the (meth)acrylate ester monomer with an alkyl group having 1 to 12carbon atoms as component (a), it is possible to use a (meth)acrylatewith an alkyl group having 1 to 12 carbon atoms other than the(meth)acrylic monomer containing a crosslinkable functional group ascomponent (b), with the use of a (meth)acrylate with an alkyl grouphaving 2 to 8 carbon atoms being more preferred. Namely, thealkyl(meth)acrylate provides the resulting pressure-sensitive adhesivewith reduced cohesive force if its alkyl group is in the form of a longchain. To retain cohesive force under high temperatures, the carbonnumber of the alkyl group may be preferably in the range of from 1 to12, more preferably in the range of from 2 to 8.

Specific examples of the (meth)acrylate ester monomer includebutyl(meth)acrylate, 2-ethylhexyl(meth)acrylate, ethyl(meth)acrylate,methyl(meth)acrylate, n-propyl(meth)acrylate, isopropyl(meth)acrylate,t-butyl(meth)acrylate, pentyl(meth)acrylate, n-octyl(meth)acrylate,isooctyl(meth)acrylate, isononyl(meth)acrylate, and the like. These(meth)acrylate ester monomers can be used either alone or in combinationof two or more.

The at least one of the vinyl monomer and (meth)acrylic monomer each ofwhich contains the crosslinkable functional group as component (b)reacts with the crosslinking agent to impart cohesive force and adhesiveforce by chemical bonds such that no failure takes place in the cohesiveforce of the resulting pressure-sensitive adhesive under conditions ofhigh temperature or high temperature and high humidity. As the mixingamount of the monomer as component (b), it may be used preferably in anamount of 0.1 to 10 parts by weight, notably 1 to 9 parts weight in 100parts by weight of the monomers to be copolymerized. A mixing amountsmaller than 0.1 parts by weight may induce a cohesion failure underhigh temperature and high humidity, while a mixing amount greater than10 parts by weight may become a cause of a substantial decrease incompatibility and a surface migration so that flowability may decreaseand cohesive force may increase, resulting in lowered stress relievingcapacity.

Examples of the vinyl monomer and (meth)acrylic monomer each of whichcontains the crosslinkable functional group as component (b) include,but are not limited to, monomers containing one or more hydroxyl groupssuch as 2-hydroxyethyl(meth)acrylate, 3-hydroxypropyl(meth)acrylate,4-hydroxybutyl(meth)acrylate, diethylene glycol mono(meth)acrylate anddipropylene glycol mono(meth)acrylate; monomers containing one or morecarboxyl groups such as (meth)acrylic acid, (meth)acrylic acid dimer,itaconic acid, maleic acid and maleic acid anhydride; monomerscontaining a hydrolyzable silyl groups such as(meth)acryloxypropyltrimethoxysilane,(meth)acryloxypropyltriethoxysilane,(meth)acryloxypropylmethyldimethoxysilane,(meth)acryloxypropylmethyldiethoxysilane,(meth)acryloxymethyltrimethoxysilane,(meth)acryloxymethyltriethoxysilane,(meth)acryloxymethylmethyldimethoxysilane and(meth)acryloxymethylmethyldiethoxysilane; and the like. These monomerscan be used either alone or in combination of two or more.

It is to be noted that in the present invention, copolymerizablemonomers other than the above-described monomers can be additionallyused upon production of the acrylic copolymer to adjust the glasstransition point of the pressure-sensitive adhesive composition and alsoto impart other functionality. Described specifically, a copolymerizablemonomer such as acrylonitrile, styrene, glycidyl(meth)acrylate or vinylacetate can be used. The mixing amount of such a copolymerizable monomermay be preferably from 0.1 to 9.9 parts by weight, more preferably from0.5 to 8 parts by weight in 100 parts by weight of the monomers to becopolymerized.

As viscoelastic properties of a pressure-sensitive adhesive compositionare determined primarily by the molecular weight and molecular weightdistribution of the polymer chain and the existing amount of themolecular structures, especially by the molecular weight. The molecularweight (weight average molecular weight: Mw) of the (meth)acryliccopolymer for use in the present invention may be preferably from800,000 to 2,000,000, more preferably from 900,000 to 1,900,000. It isto be noted that each weight average molecular weight is a value asdetermined by gel permeation chromatography (GPC) using a polystyrenestandard. An excessively low molecular weight may fail to obtain desiredviscoelastic properties, while an unduly high molecular weight mayprovide the resultant polymer with very high viscosity to make itshandling difficult so that the productivity may be lowered.

The copolymer can be produced through a conventional radicalpolymerization step. No particular limitation is imposed on thepolymerization process of the copolymer in the present invention, andthe copolymer can be produced by a general process such as solutionpolymerization, photopolymerization, bulk polymerization, suspensionpolymerization or emulsion polymerization. Of these, solutionpolymerization is preferred from the viewpoint of productivity. Insolution polymerization, the polymerization temperature may preferablybe from 50 to 140° C. and the reaction time may preferably be from 1 to24 hours. It is preferred to add an initiator after the monomers havebeen formed into a uniform mixture.

In the pressure-sensitive adhesive composition according to the presentinvention, the polyfunctional crosslinking agent as component (B) playsa role to provide the resulting pressure-sensitive adhesive withenhanced cohesive force through its reaction with carboxyl groups and/orhydroxyl groups. The content of the crosslinking agent may be preferablyfrom 0.01 to 10 parts by weight, more preferably from 0.05 to 5 parts byweight per 100 parts by weight of the copolymer as component (A). Anunduly high content may result in severe cohesion so that the formationinto a pressure-sensitive adhesive sheet or the like may be rendereddifficult. An excessively low content, on the other hand, may fail tobring about the cohesive force enhancing effect as desired.

As the polyfunctional crosslinking agent, an isocyanate, epoxy,aziridine, metal chelate crosslinking agents can be used. Of these, anisocyanate crosslinking agent is easy to use. Specific examples of theisocyanate crosslinking agent include tolylene diisocyanate, xylenediisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate,isoform diisocyanate, tetramethylxylene diisocyanate, naphthalenediisocyanate, and their reaction products with polyols such astrimethylolpropane.

Specific examples of the epoxy crosslinking agent include ethyleneglycol diglycidyl ether, trimethylolpropane triglycidyl ether,N,N,N′,N′-tetraglycidylethylenediamine, glycerin diglycidyl ether,glycerin triglycidyl ether, polyglycerin polyglycidyl ether, sorbitolpolyglycidyl ethers, and the like.

Specific examples of the aziridine crosslinking agent includeN,N′-toluene-2,4-bis(1-aziridinecarboxide),N,N′-diphenylmethane-4,4′-bis(1-aziridinecarboxide),triethylenemelamine, bisisoprotaloyl-1-(2-methylaziridine),tri-1-aziridinylphosphine oxide, and the like.

Examples of the metal chelate crosslinking agent include compounds thatmultivalent metals such as aluminum, iron, zinc, tin, titanium,antimony, magnesium and vanadium coordinate with acetyl acetone or ethylacetoacetate, and the like.

As the organosilicon compound as component (C), it is preferred to useone of the above-described silane coupling agents having coordinatefunctional groups and represented by the formulas (1) to (3). Byincorporating the silane coupling agent in the pressure-sensitiveadhesive composition, the initial rework capability and the adhesiveforce under high temperature and high humidity are significantlyimproved. The specific structures of the silane coupling agents are asdescribed above, and these silane coupling agents can be used eitheralone or in combination of two or more. Its mixing amount may bepreferably from 0.01 to 9 parts by weight, more preferably from 0.1 to 5parts by weight, particularly preferably from 0.1 to 3 parts by weightper 100 parts by weight of the (meth)acrylic copolymer (A). Its contentlower than 0.01 parts by weight may not be able to fully bring about theadvantageous effects available from the addition of the silane, whileits content higher than 9 parts by weight involves a potential problemthat due to its use in the excess amount, bubbles or separation mayoccur to result in reduced durability.

In the present invention, a tackiness-imparting resin can be addedfurther to adjust the adhesion performance of the composition. Itscontent may be in a range of from 1 to 100 parts by weight, especiallyfrom 5 to 90 parts by weight per 100 parts by weight of the(meth)acrylic copolymer (A). A content lower than 1 parts by weight maynot exhibit sufficient adjusting effect, while a content higher than 100parts by weight involves a potential problem of providing the resultingadhesive with reduced common utility or cohesive property.

Usable examples of the tackiness-imparting resin include (hydrogenated)hydrocarbon resins, (hydrogenated) rosin resins, (hydrogenated) rosinester resins, (hydrogenated) terpene resins, (hydrogenated) terpenephenol resins, polymerized rosin resins, polymerized rosin ester resins,and the like. They can be used either alone or in combination of two ormore.

In addition to the above-described components, plasticizers,low-molecular-weight substances such as leveling agents, epoxy resins,curing agents and the like can be used as additional components incombination, and further, ultraviolet stabilizers, antioxidants, colorremovers, reinforcing agents, fillers, defoaming agent, surfactants andthe like can be appropriately added and used depending on theapplication purpose.

No particular limitation is imposed on the production method of thepressure-sensitive adhesive composition according to the presentinvention, and the pressure-sensitive adhesive composition can beobtained by mixing (A) the (meth)acrylic copolymer, (B) thepolyfunctional crosslinking agent and (C) the silane coupling agent in ausual manner. As mixing conditions, the mixing may be conductedpreferably at 10 to 150° C. for 10 minutes to 10 hours. In thisproduction, the silane coupling agent having the coordinate functionalgroups can be used by adding it in a mixing step after thepolymerization of the (meth)acrylic copolymer. The silane coupling agentcan exhibit the same effect even when it is added in the course of theproduction process of the (meth)acrylic copolymer. Further, uniformcoating of the pressure-sensitive adhesive composition is feasible whenno substantial crosslinking reactions of functional groups by thepolyfunctional crosslinking agent take place in the mixing stepconducted for the formation of a pressure-sensitive adhesive layer to beobtained by curing the pressure-sensitive adhesive composition. Throughdrying and aging steps after the coating, a crosslinked structure isformed so that a pressure-sensitive adhesive layer having elasticity andhigh cohesive force can be obtained.

The pressure-sensitive adhesive composition of this invention obtainedas described above can form a pressure-sensitive adhesive layer whencoated the composition on an adherend such as a glass plate, plasticfilm or paper sheet and cured at 25 to 150° C. and 20 to 90% RH for 5minutes to 5 hours, especially at 40 to 80° C. and 25 to 60% RH for 10minutes to 3 hours.

It is desired to use the pressure-sensitive adhesive composition of theinvention after fully eliminating components which otherwise induce theformation of bubbles inside, such as volatile components and reactionresidues. If the crosslink density and molecular weight are excessivelylow and the coefficient of elasticity of the pressure-sensitive adhesivelayer is unduly low, small bubbles which exist between an adherend suchas a glass plate and the pressure-sensitive adhesive layer become largerat a high-temperature to form scatterers inside the pressure-sensitiveadhesive layer. If a pressure-sensitive adhesive layer havingexcessively high coefficient of elasticity is used over a long term, thepressure-sensitive adhesive layer (sheet) develops separation at endpositions thereof due to excessive crosslinking reactions.

When an optimal physical balance is taken into consideration, thecrosslink density of the pressure-sensitive adhesive layer may suitablybe in a range of from 5 to 95 wt %, with a range of 7 to 93 wt % beingparticularly suited. The term “crosslink density” indicates a value thatexpresses portions where a crosslinked structure insoluble in a solventis formed in terms of wt % by the commonly-known gel content measuringmethod for pressure-sensitive adhesives. If the crosslink density of apressure-sensitive adhesive layer is lower than 5 wt %, thepressure-sensitive adhesive layer is provided with reduced cohesiveforce and therefore is accompanied by a potential problem in adhesiondurability such as bubbling or separation. If higher than 95 wt %, onthe other hand, the pressure-sensitive adhesive layer may not adherefirmly and may hence be reduced in durability.

Self-Adhesive Polarizer

A description will next be described about a self-adhesive polarizerincluding pressure-sensitive adhesive layer(s) obtained by coating andcuring the pressure-sensitive adhesive composition on one or both ofopposite sides of a polarizing film or the like.

The self-adhesive polarizer according to the present invention includesa polarizing film or polarizing device and pressure-sensitive adhesivelayer(s) formed from the above-described pressure-sensitive adhesivecomposition and applied on one or both of opposite sides of thepolarizing film or polarizing device. No particular limitation isimposed on the polarizing film or polarizing devices that constitutesthe polarizer. Examples of the polarizing film include films obtained byincorporating a polarizing component such as iodine or a heterochromaticdye in films made of a polyvinyl alcohol resin and then stretching thefilms. No particular limitation is imposed on the thickness of thesepolarizing films, so that they can be formed with a usual thickness.

As the polyvinyl alcohol resin, polyvinyl alcohol, polyvinyl formal,polyvinyl acetal, a saponification production of an ethylene-vinylacetate copolymer, or the like can be used.

As the polarizing film, it is also possible to use such a multilayerfilm that on opposite sides of a polarizing film, protective films, forexample, cellulose films such as triacetyl cellulose films, polyesterfilms such as polycarbonate films or polyethylene terephthalate films,polyethersulfone films, or polyolefin films such as polyethylene films,polypropylene films or ethylene-propylene copolymer films are laminated.No particular limitation is imposed on the thickness of these protectivefilms, so that they can be formed with a usual thickness.

In the present invention, no particular limitation is imposed on themethod for forming the pressure-sensitive adhesive layer on thepolarizing film. It is possible to adopt, for example, such a methodthat includes coating the pressure-sensitive adhesive compositiondirectly onto the surface of the polarizing film with a bar coater orthe like and drying the thus-coated adhesive composition or such amethod that includes once coating the pressure-sensitive adhesivecomposition onto a surface of a peelable base material and drying thethus-coated adhesive composition, transferring the pressure-sensitiveadhesive layer, which has been formed on the surface of the peelablebase material, onto the surface of the polarizing film, and then agingthe thus-transferred adhesive layer. In this method, the drying may beconducted preferably at 25 to 150° C. and 20 to 90% RH for 5 minutes to5 hours, and the aging may be conducted preferably at 25 to 150° C. and20 to 90% RH for 5 minutes to 5 hours.

No particular limitation is imposed on the thickness of thepressure-sensitive adhesive layer. In general, however, the thicknessmay be preferably from 0.01 to 100 μm, more preferably from 0.1 to 50μm. If the thickness of the pressure-sensitive adhesive layer is smallerthan the above-described range, its effect as the pressure-sensitiveadhesive layer may not be brought about fully. If the thickness of thepressure-sensitive adhesive layer is greater than the above-describedrange, on the other hand, the effect of the pressure-sensitive adhesivelayer may reach saturation and may result in higher cost.

On the polarizing film with the pressure-sensitive adhesive layerapplied thereon as described above (on the self-adhesive polarizeraccording to the present invention), it is possible to laminate one ormore of layers providing additional functions such as a protectivelayer, a reflective layer, a retardation film, an optical view-anglecompensation film, and a luminance enhancement film.

Liquid Crystal Display

The self-adhesive polarizer according to the present invention can beapplied specifically to any one of usual liquid crystal displays, and noparticular limitation is imposed on the kind of its liquid crystalpanel. In particular, it is preferred to construct a liquid crystaldisplay by including a liquid crystal panel with one or twoself-adhesive polarizers of the present invention bonded on one or bothof opposite sides of a liquid crystal cell composed of a pair of glasssubstrates and a liquid crystal sealed therebetween.

The self-adhesive composition according to the present invention can beused irrespective of applications, especially to industrial sheets suchas, in addition to the above-described polarizing films, reflectingsheets, structural self-adhesive sheets, photographic self-adhesivesheets, lane-marking self-adhesive sheets, optical self-adhesiveproducts, and electronic parts and components. It can also be used inapplication fields which are similar in action concept such as laminatedproducts of multilayer structures, specifically general commercialself-adhesive sheet products, medical patches, heat activable products,and the like.

The pressure-sensitive adhesive composition according to the presentinvention is a (meth)acrylic pressure-sensitive adhesive containing asilane coupling agent having coordinate functional groups. As itsinitial adhesive force is low upon boding to glass or the like, reworkcapability is excellent. After moisture/heat exposure subsequent to thebonding, sufficiently high adhesive force is developed to provideexcellent long-term durability.

EXAMPLES

The present invention will hereinafter be described more specificallybased on Synthesis Examples, Examples and Comparative Examples, althoughthe present invention shall not be limited to these Examples. It is tobe noted that in the following examples, viscosities, specific gravitiesand refractive indexes are values measured as 25° C. Further, “NMR,”“IR” and “GPC” are abbreviations of nuclear magnetic resonancespectroscopy, infrared spectroscopy and gel permeation chromatography,respectively. Viscosities are based on measurements at 25° C. by acapillary kinematic viscometer.

Synthesis Example 1

In a 1-L separable flask equipped with a stirrer, a reflux condenser, adropping funnel and a thermometer, 31.4 g (0.33 mol) of 2-aminopyridinewas placed, followed by charging of 150 g of tetrahydrofuran. Theresultant mixture was stirred into a solution. Into the solution, 82.5 g(0.33 mol) of 3-isocyanatopropyltriethoxysilane was charged dropwise,and the thus-obtained mixture was stirred under heating at 70° C. for 4hours. Subsequently, it is confirmed by IR measurement that anabsorption peak attributable to the isocyanato group in the reactant3-isocyanatopropyltriethoxysilane had disappeared completely andinstead, an absorption peak attributable to a urea bond had been formed,the reaction was determined to be completed. The solvent was thendistilled off to obtain the reaction product, which was a pale yellowliquid and had a viscosity of 184 mm²/s, a specific gravity of 1.094 anda refractive index of 1.4975. The reaction product was confirmed by GPCto be consisted of a single product, and was also confirmed by NMRspectroscopy to have a structure represented by the below-describedchemical structural formula (8). A proton NMR spectrum of this compoundis shown in FIG. 1, a carbon NMR spectrum in FIG. 2, a silicon NMRspectrum in FIG. 3, an IR spectrum in FIG. 4, and a GPC chart in FIG. 5.

wherein Et represents an ethyl group, and this definition will applyequally hereinafter.

Synthesis Example 2

In a 1-L separable flask equipped with a stirrer, a reflux condenser, adropping funnel and a thermometer, 31.7 g (0.33 mol) of2-aminopyrimidine was placed, followed by charging of 150 g oftetrahydrofuran. The resultant mixture was stirred into a solution. Intothe solution, 82.5 g (0.33 mol) of 3-isocyanatopropyltriethoxysilane wascharged dropwise, and the thus-obtained mixture was stirred underheating at 70° C. for 4 hours. Subsequently, it is confirmed by IRmeasurement that an absorption peak attributable to the isocyanato groupin the reactant 3-isocyanatopropyltriethoxysilane had disappearedcompletely and instead, an absorption peak attributable to a urea bondhad been formed, the reaction was determined to be completed. Thesolvent was then distilled off to obtain the reaction product, which wasan orange solid. The reaction product was confirmed by NMR spectroscopyto have the below-described chemical structural formula (9). Its NMRspectral data are as follows:

¹H-NMR (300 MHz, CDCl₃, δ(ppm)): 0.58 (t, 2H), 1.07 (t, 9H), 1.61(quint, 2H), 3.28 (t, 2H), 3.67 (q, 6H), 6.66 (m, 1H), 6.88 (m, 1H),7.39 (m, 1H), 7.97 (m, 1H), 9.34 (s, 1H), 10.01 (s, 1H).

¹³C-NMR (75 MHz, CDCl₃, δ(ppm)): 7.6, 18.2, 23.2, 42.2, 58.0, 110.8,113.7, 158.0, 163.2.

²⁹Si-NMR (60 MHz, CDCl₃, δ(ppm)): −45.7.

Synthesis Example 3

In a 1-L separable flask equipped with a stirrer, a reflux condenser, adropping funnel and a thermometer, 89.4 g (0.75 mol) of2-mercaptothiazoline and 1.3 g of dioctyltin oxide were placed, followedby charging of 300 g of ethyl acetate. The resultant mixture was stirredinto a solution. Into the solution, 185.5 g (0.75 mol) of3-isocyanatopropyltriethoxysilane was charged dropwise, and thethus-obtained mixture was stirred under heating at 80° C. for 4 hours.Subsequently, it is confirmed by IR measurement that an absorption peakattributable to the isocyanato group in the reactant3-isocyanatopropyltriethoxysilane had disappeared completely andinstead, an absorption peak attributable to a thiourethane bond had beenformed, the reaction was determined to be completed. The solvent wasthen distilled off to obtain the reaction product, which was a paleyellow liquid and had a viscosity of 38 mm²/s, a specific gravity of1.164 and a refractive index of 1.5218. The reaction product wasconfirmed by NMR spectroscopy to have the below-described chemicalstructural formula (10). Its NMR spectral data are as follows:

¹H-NMR (300 MHz, CDCl₃, δ(ppm)): 0.38 (t, 2H), 0.94 (t, 9H), 1.40(quint, 2H), 3.02 (m, 2H), 3.04 (t, 2H), 3.54 (q, 6H), 4.42 (m, 2H),9.52 (s, 1H).

¹³C-NMR (75 MHz, CDCl₃, δ(ppm)): 7.2, 17.7, 22.2, 26.6, 42.5, 55.8,57.8, 151.6, 199.6.

²⁹Si-NMR (60 MHz, CDCl₃, δ(ppm)): −45.7.

Synthesis Example 4

In a 1-L separable flask equipped with a stirrer, a reflux condenser, adropping funnel and a thermometer, 33.4 g (0.33 mol) of 2-aminothiazolewas placed, followed by charging of 150 g of tetrahydrofuran. Theresultant mixture was stirred into a solution. Into the solution, 82.5 g(0.33 mol) of 3-isocyanatopropyltriethoxysilane was charged dropwise,and the thus-obtained mixture was stirred under heating at 80° C. for 4hours. Subsequently, it is confirmed by IR measurement that anabsorption peak attributable to the isocyanato group in the reactant3-isocyanatopropyltriethoxysilane had disappeared completely andinstead, an absorption peak attributable to a urea bond had been formed,the reaction was determined to be completed. The solvent was thendistilled off to obtain the reaction product, which was a brown solid.The reaction product was confirmed by NMR spectroscopy to have thebelow-described chemical structural formula (11). Its NMR spectral dataare as follows:

¹H-NMR (300 MHz, CDCl₃, δ(ppm)): 0.65 (t, 2H), 1.19 (t, 9H), 1.68(quint, 2H), 3.32 (t, 2H), 3.69 (m, 1H), 3.79 (q, 6H), 6.26 (m, 2H),7.28 (m, 2H).

¹³C-NMR (75 MHz, CDCl₃, δ(ppm)): 7.7, 18.2, 23.4, 42.7, 58.3, 111.0,136.8, 154.8, 162.6.

²⁹Si-NMR (60 MHz, CDCl₃, δ(ppm)): −45.8.

Synthesis Example 5

In a 1-L separable flask equipped with a stirrer, a reflux condenser, adropping funnel and a thermometer, 50.1 g (0.33 mol) of2-aminobenzothiazole was placed, followed by charging of 150 g oftetrahydrofuran. The resultant mixture was stirred into a solution. Intothe solution, 82.5 g (0.33 mol) of 3-isocyanatopropyltriethoxysilane wascharged dropwise, and the thus-obtained mixture was stirred underheating at 70° C. for 4 hours. Subsequently, it is confirmed by IRmeasurement that an absorption peak attributable to the isocyanato groupin the reactant 3-isocyanatopropyltriethoxysilane had disappearedcompletely and instead, an absorption peak attributable to a urea bondhad been formed, the reaction was determined to be completed. Thesolvent was then distilled off to obtain the reaction product, which wasa white solid. The reaction product was confirmed by NMR spectroscopy tohave the below-described chemical structural formula (12). Its NMRspectral data are as follows:

¹H-NMR (300 MHz, CDCl₃, δ(ppm)): 0.68 (t, 2H), 1.20 (t, 9H), 1.71(quint, 2H), 3.35 (t, 2H), 3.53 (m, 1H), 3.72 (q, 1H), 3.81 (q, 6H),7.21 (m, 1H), 7.35 (m, 1H), 7.68 (m, 2H).

¹³C-NMR (75 MHz, CDCl₃, δ(ppm)): 7.4, 18.2, 23.2, 42.7, 58.4, 119.8,121.1, 123.3, 126.0, 130.8, 149.0, 154.7, 161.7.

²⁹Si-NMR (60 MHz, CDCl₃, δ(ppm)): −45.9.

Synthesis Example 6

In a 1-L separable flask equipped with a stirrer, a reflux condenser, adropping funnel and a thermometer, 57.5 g (0.5 mol) ofN-hydroxysuccinimide and 1.0 g of dioctyltin oxide were placed, followedby charging of 300 g of tetrahydrofuran. The resultant mixture wasstirred into a solution. Into the solution, 123.7 g (0.5 mol) of3-isocyanatopropyltriethoxysilane was charged dropwise, and thethus-obtained mixture was stirred under heating at 70° C. for 4 hours.Subsequently, it is confirmed by IR measurement that an absorption peakattributable to the isocyanato group in the reactant3-isocyanatopropyltriethoxysilane had disappeared completely andinstead, an absorption peak attributable to a urethane bond had beenformed, the reaction was determined to be completed. The solvent wasthen distilled off to obtain the reaction product, which was a paleyellow liquid and had a viscosity of 38 mm²/s, a specific gravity of1.164 and a refractive index of 1.5218. The reaction product wasconfirmed by NMR spectroscopy to have the below-described chemicalstructural formula (13). Its NMR spectral data are as follows:

¹H-NMR (300 MHz, CDCl₃, δ(ppm)): 0.35 (t, 2H), 0.94 (t, 9H), 1.38(quint, 2H), 2.39 (m, 2H), 2.52 (m, 2H), 2.90 (t, 2H), 3.53 (q, 6H),4.42 (m, 2H), 6.45 (m, 1H).

¹³C-NMR (75 MHz, CDCl₃, δ(ppm)): 6.8, 17.6, 22.2, 24.8, 43.7, 57.7,151.2, 170.2.

²⁹Si-NMR (60 MHz, CDCl₃, δ(ppm)): −45.4.

Synthesis Example 7

In a 1-L separable flask equipped with a stirrer, a reflux condenser, adropping funnel and a thermometer, 48.9 g (0.3 mol) ofN-hydroxyphthalimide and 1.0 g of dioctyltin oxide were placed, followedby charging of 200 g of ethyl acetate. The resultant mixture was stirredinto a solution. Into the solution, 74.2 g (0.3 mol) of3-isocyanatopropyltriethoxysilane was charged dropwise, and thethus-obtained mixture was stirred under heating at 80° C. for 4 hours.Subsequently, it is confirmed by IR measurement that an absorption peakattributable to the isocyanato group in the reactant3-isocyanatopropyltriethoxysilane had disappeared completely andinstead, an absorption peak attributable to a urethane bond had beenformed, the reaction was determined to be completed. The solvent wasthen distilled off to obtain the reaction product, which was a yellowsolid. The reaction product was confirmed by NMR spectroscopy to havethe below-described chemical structural formula (14). Its NMR spectraldata are as follows:

¹H-NMR (300 MHz, CDCl₃, δ(ppm)): 0.60 (t, 2H), 1.14 (t, 9H), 1.65(quint, 2H), 3.20 (m, 2H), 3.75 (q, 6H), 6.30 (m, 1H), 7.72 (m, 4H).

¹³C-NMR (75 MHz, CDCl₃, δ(ppm)): 7.3, 17.9, 22.6, 44.2, 58.3, 123.6,128.7, 134.5, 152.2, 162.4.

²⁹Si-NMR (60 MHz, CDCl₃, δ(ppm)): −45.9.

Synthesis Example 8

In a 1-L separable flask equipped with a stirrer, a reflux condenser, adropping funnel and a thermometer, 53.2 g (0.3 mol) ofN-hydroxymethylphthalimide and 1.0 g of dioctyltin oxide were placed,followed by charging of 200 g of ethyl acetate. The resultant mixturewas stirred into a solution. Into the solution, 74.2 g (0.3 mol) of3-isocyanatopropyltriethoxysilane was charged dropwise, and thethus-obtained mixture was stirred under heating at 80° C. for 4 hours.Subsequently, it is confirmed by IR measurement that an absorption peakattributable to the isocyanato group in the reactant3-isocyanatopropyltriethoxysilane had disappeared completely andinstead, an absorption peak attributable to a urethane bond had beenformed, the reaction was determined to be completed. The solvent wasthen distilled off to obtain the reaction product, which was a whitesolid. The reaction product was confirmed by NMR spectroscopy to havethe below-described chemical structural formula (15). Its NMR spectraldata are as follows:

¹H-NMR (300 MHz, CDCl₃, δ(ppm)): 0.49 (t, 2H), 1.07 (t, 9H), 1.49(quint, 2H), 3.04 (m, 2H), 3.68 (q, 6H), 5.39 (m, 1H), 5.55 (s, 2H),7.69 (m, 4H).

¹³C-NMR (75 MHz, CDCl₃, δ(ppm)): 7.3, 14.3, 17.9, 22.7, 43.1, 57.9,123.2, 131.4, 134.1, 154.5, 166.4.

²⁹Si-NMR (60 MHz, CDCl₃, δ(ppm)): −45.6.

Synthesis Example 9

In a 1-L separable flask equipped with a stirrer, a reflux condenser, adropping funnel and a thermometer, 98.1 g of n-butyl acrylate(BA), 0.6 gof acrylic acid(AA) and 1.3 g of 2-hydroxyethyl methacrylate(2-HEMA)were placed, followed by charging of 100 g of ethyl acetate as asolvent. The resultant mixture was stirred into a solution.Subsequently, nitrogen gas bubbling was conducted for 1 hour to removeoxygen so that the interior of the reaction system was purged withnitrogen, and the reaction system was maintained at 62° C. Into thereaction system, 0.03 g of azobisisobutyronitrile was charged as apolymerization initiator under stirring, followed by a reaction at 62°C. for 8 hours to obtain a (meth)acrylic copolymer as a base polymer.

Examples 1 to 8

With 100 parts by weight of the (meth)acrylic copolymer obtained inSynthesis Example 9, a trimethylolpropane-tolylene diisocyanate adduct(TDI) as a crosslinking agent and the silane coupling agent obtained inSynthesis Example 1 were mixed in accordance with the correspondingformula shown in Table 1 to obtain a pressure-sensitive adhesivecomposition. Using the silane coupling agents obtained in SynthesisExamples 2 to 8, pressure-sensitive adhesive compositions were likewiseobtained in accordance with the corresponding formulas shown in Table 1,respectively.

The thus-obtained pressure-sensitive adhesive compositions wereseparately coated on release paper sheets, and were then dried to obtainuniform pressure-sensitive adhesive layers of 25 μm. Thepressure-sensitive adhesive layers prepared as described above werebonded on iodine-based polarizers of 185 μm thickness, respectively. Thethus-obtained polarizers were then cut into suitable sizes for use invarious evaluations.

The thus-produced test pieces of the respective polarizers wereevaluated for durability, glass adhesion properties, rework capability,and variations in adhesive force under high temperature or hightemperature and high humidity conditions in accordance with theevaluation testing methods to be described subsequently herein. Theevaluation results are shown in Tables 2 to 4.

Comparative Examples 1 to 3

Following a similar procedure and formulas as in the above-describedexamples except that the silane coupling agents B-1 to B-3 shown inTable 1 were used in place of the silane coupling agents of the presentinvention, pressure-sensitive adhesive compositions were produced, and alamination processing step was conducted. With respect to thethus-obtained test pieces, similar evaluations were also performed as inthe examples. The evaluation results are shown in Tables 2 to 4.

It is to be noted that the abbreviations in Table 1 have the followingmeanings:

n-BA: n-butyl acrylate

AA: acrylic acid

2-HEMA: 2-hydroxyethyl methacrylate

TDI: tolylene diisocyanate adduct of trimethylolpropane, crosslinkingagent

Silane A-1: compound of Synthesis Example 1

Silane A-2: compound of Synthesis Example 2

Silane A-3: compound of Synthesis Example 3

Silane A-4: compound of Synthesis Example 4

Silane A-5: compound of Synthesis Example 5

Silane A-6: compound of Synthesis Example 6

Silane A-7: compound of Synthesis Example 7

Silane A-8: compound of Synthesis Example 8

Silane B-1:

Silane B-2: γ-glycidoxypropyltrimethoxysilane

-   -   (“KBM-403,” product of Shin-Etsu Chemical Co., Ltd.)        Silane B-3: γ-isocyanatopropyltriethoxysilane    -   (“KBE-9007,” product of Shin-Etsu Chemical Co., Ltd.)

TABLE 1 Comparative Example Example Parts by weight 1 2 3 4 5 6 7 8 1 23 Formula Copolymer n-BA 98.1 98.1 98.1 98.1 98.1 98.1 98.1 98.1 98.198.1 98.1 composition AA 0.6 0.6 0.6 0.6 0.6 0.6 0.6 0.6 0.6 0.6 0.6 2-1.3 1.3 1.3 1.3 1.3 1.3 1.3 1.3 1.3 1.3 1.3 HEMA Crosslinking TDI 0.50.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 agent Silanes A-1 1 0 0 0 0 0 00 0 0 0 A-2 0 1 0 0 0 0 0 0 0 0 0 A-3 0 0 1 0 0 0 0 0 0 0 0 A-4 0 0 0 10 0 0 0 0 0 0 A-5 0 0 0 0 1 0 0 0 0 0 0 A-6 0 0 0 0 0 1 0 0 0 0 0 A-7 00 0 0 0 0 1 0 0 0 0 A-8 0 0 0 0 0 0 0 1 0 0 0 B-1 0 0 0 0 0 0 0 0 1 0 0B-2 0 0 0 0 0 0 0 0 0 1 0 B-3 0 0 0 0 0 0 0 0 0 0 1Evaluation Tests[Durability]

The durability of each polarizer was evaluated as will be describedhereinafter. Two of the test pieces of the polarizer having the adhesivelayer (90 mm×170 mm) were bonded on opposite sides of a glass substrate(110 m×190 mm×0.7 mm) in such a way that the optical absorption axes ofthe two test pieces cross over each other, whereby a laminate sample wasprepared. The pressure applied upon bonding was approximately 5 kgf/cm²,and the work was conducted in a clean room to avoid bubbles or dustparticles. The above procedure was repeated to prepare other laminatesamples.

To evaluate the moisture and heat resistance of those test pieces, thelaminate samples were left over for 1,000 hours under the conditions of60° C./90% RH, and then observed whether bubbles or separation had beendeveloped. To evaluate the heat resistance of those test pieces, on theother hand, the laminate samples were left over for 1,000 hours underthe conditions of 80° C./30% RH, and then observed for any bubbles orseparation. It is to be noted that before the respective evaluations ofthe laminate samples, they were allowed to stand at room temperature(25° C.) for 24 hours. The results are shown in Table 2.

The following standards were employed for the evaluation of durability.

A: Neither bubbles nor separation occurred.

B: Bubbles and separation occurred slightly.

C: Bubbles and separation occurred significantly.

[Glass Adhesion Properties, and Variations in Adhesive Force Under HighTemperature or High Temperature and High Humidity Conditions]

Glass adhesion properties and variations in adhesive force under hightemperature or high temperature and high humidity conditions of eachpolarizer were evaluated as will be described hereinafter. After two ofthe test pieces of the polarizer having the adhesive layer were aged for7 days at room temperature (23° C./60% RH), the test pieces were cutinto equal sizes of 1 inch×6 inches. Using a 2-kg rubber roller, thetest pieces were bonded onto alkali-free glass substrates of 0.7 mmthickness, respectively, to prepare laminate samples. Upon an elapsedtime of 1 hour after being stored at room temperature, the laminatesamples were measured for initial adhesive force. The laminate sampleswere then aged at 50° C. for 4 hours, and subsequent to storage at roomtemperature for 1 hour, its adhesive force was measured. The results areshown in Table 2.

To determine the degrees of increases in adhesive force under hightemperature conditions and high temperature and high humidityconditions, laminate samples prepared by a similar procedure asdescribed above were aged separately under conditions of 60° C./30% RHand conditions of 60° C./90% RH for respective times. Subsequent to theaging, each laminate sample was allowed to cool down at room temperaturefor 1 hour, and its adhesive force was then measured. The results areshown in Tables 3 and 4. For the measurement of the adhesive force, atensile testing machine was used, and peeling strength was measured at apeeling rate of 300 mm/min and an angle of 180°.

[Rework Capability]

The rework capability of each polarizer was evaluated as will bedescribed hereinafter. The test piece of the polarizer having theadhesive layer (90 mm×170 mm) was bonded on a glass substrate (110mm×190 mm×0.7 mm) to prepare a laminate sample. After an elapsed time of1 hour at room temperature initial bonding was measured, and thelaminate sample was aged at 50° C. for 4 hours. After the laminatesample was allowed to cool down at room temperature for 1 hour, the testpiece was peeled off from the glass substrate. The results are shown inTable 2.

The following standards were employed for the evaluation of reworkcapability.

A: Easy to separate.

B: A little hard to separate.

C: Impossible to separate, or glass substrate is broken.

The following Tables 2 to 4 summarize the evaluation results of thepolarizers on which the pressure-sensitive adhesive compositions of theexamples and comparative examples were applied, for durability, glassadhesion force, rework capability and variations in adhesive force underhigh temperature and under high temperature and high humidity asobtained in accordance with the above-described evaluation methods.

TABLE 2 Glass adhesion force (gf/in) Durability/reliability Initial 60°C., 80° C., adhesive 50° C. 90% RH 30% RH Rework force 4 hr 1000 hr 1000hr capability Example 1 380 650 A A A 2 390 780 A A A 3 400 770 A A A 4390 810 A A A 5 380 840 A A A 6 430 820 A A A 7 380 950 A A A 8 370 880A A A Com- 1 380 530 A B A parative 2 1000 1500 B A C Example 3 320 350B B C

TABLE 3 Variations in glass adhesion force (gf/in) under hightemperature Holding Comparative conditions Example Example 60° C., 30%RH 1 2 3 4 5 6 7 8 1 2 3 Initial 380 390 400 390 380 430 380 370 3801000 320  2 hours 510 600 530 680 670 670 710 680 450 1300 380  6 hours650 780 770 810 840 820 950 880 490 1970 410  1 day 810 900 870 920 950920 1000 960 570 2000 530  3 days 1300 1350 1340 1420 1400 1450 15801400 1060 2760 780  6 days 2120 2200 2180 2290 2300 2380 2450 2400 16603870 800 10 days 2700 2760 2810 2930 2950 3010 3100 2990 2240 4060 79015 days 3040 3110 3170 3290 3310 3360 3480 3450 2600 4120 850 20 days3040 3120 3190 3290 3330 3380 3510 3460 2650 4860 900

TABLE 4 Variations in glass adhesion force (gf/in) under hightemperature and high humidity Holding Comparative conditions ExampleExample 60° C., 90% RH 1 2 3 4 5 6 7 8 1 2 3 Initial 380 390 400 390 380430 380 370 380 1000 320  2 hours 500 580 550 620 600 630 700 600 4301500 330  6 hours 670 730 720 750 880 840 1000 810 500 2000 400  1 day860 920 870 920 1040 930 1050 920 650 2540 440  3 days 1360 1410 13801450 1430 1480 1620 1430 1000 2670 450  6 days 2110 2190 2150 2240 22802350 2430 2350 1630 4000 460 10 days 2680 2730 2770 2880 2900 2990 30603000 2120 4250 560 15 days 3030 3090 3140 3250 3200 3310 3410 3380 22004860 590 20 days 3050 3100 3160 3250 3210 3330 3440 3390 2600 4960 480

The above-described results substantiate that the pressure-sensitiveadhesive composition according to the present invention is excellent ininitial rework capability, and after exposure to high temperature orhigh temperature and high humidity, can develop sufficient adhesiveforce of excellent long-term durability with glass.

Japanese Patent Application No. 2008-227777 is incorporated herein byreference.

Although some preferred embodiments have been described, manymodifications and variations may be made thereto in light of the aboveteachings. It is therefore to be understood that the invention may bepracticed otherwise than as specifically described without departingfrom the scope of the appended claims.

The invention claimed is:
 1. A pressure-sensitive adhesive compositioncomprising a organosilicon compound represented by the following formula(1):

wherein R is a hydrolyzable group, R′ is an alkyl group having 1 to 4carbon atoms, A is a linear or branched alkylene group having 1 to 6carbon atoms, x is an oxygen atom or sulfur atom, Y is —NH— or a sulfuratom, L1 and L2 are each independently a carbon atom or nitrogen atom,R1 to R3 are each independently a hydrogen atom, an alkyl, alkoxy orfluoroalkyl group having 1 to 6 carbon atoms, or an amino group, R1 andR2 or R2 and R3 may bond together to form a ring skeleton with thecarbon atoms to which they are bonded and L2, m is an integer of 1 to 3,and n is an integer of 0 to
 3. 2. The pressure-sensitive adhesivecomposition according to claim 1, comprising: (A) 100 parts by weight ofa (meth)acrylic copolymer obtainable by copolymerizing (a) 90 to 99.9parts by weight of a (meth)acrylate ester monomer having an alkyl grouphaving 1 to 12 carbon atoms and (b) 0.1 to 10 parts by weight of atleast one of a vinyl monomer and (meth)acrylic monomer each of whichcontains a crosslinkable functional group, (B) 0.01 to 10 parts byweight of a polyfunctional crosslinking agent, and (C) 0.01 to 9 partsby weight of the organosilicon compound according to claim
 1. 3. Thepressure-sensitive adhesive composition according to claim 2, wherein atleast one of the vinyl monomer and (meth)acrylic monomer (b) is selectedfrom a group consisting of 2-hydroxyethyl(meth)acrylate,3-hydroxpropyl(meth)acrylate, 4-hydroxybutyl(meth)acrylate, diethyleneglycol mono(meth)acrylate, dipropylene glycol mono(meth)acrylate,(meth)acryloxypropyltrimethoxysilane,(meth)acryloxypropyltriethoxysilane,(meth)acryloxpropylmethyldimethoxysilane,(meth)acryloxypropylmethyldiethoxysilane,(meth)acryloxymethyltrimethoxysilane,(meth)acryloxymethyltriethoxysilane,(meth)acryloxymethylmethyldimethoxysilane,(meth)acryloxymethylmethyldiethoxysilane, (meth)acrylic acid,(meth)acrylic acid dimmer, itaconic acid, maleic acid, and maleic acidanhydride.
 4. The pressure-sensitive adhesive composition according toclaim 2, wherein the polyfunctional crosslinking agent (B) is at leastone crosslinking agent selected from a group consisting of isocyanatecompounds, epoxy compounds, aziridine compounds and metal chelatecompounds.
 5. The pressure-sensitive adhesive composition according toclaim 1, which is cured into a product having a crosslink density of 5to 95 wt %.